{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.685","julian_year":2026.685,"time":"2026-09-08T07:10:37.106Z","years_from_j2000":26.685,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, and the result is referred to the true equator and equinox of this instant. Those are separate things: the motion moves the object, and the rotation turns the grid under it by about fifty arcseconds a year, with nutation adding up to another seventeen.","excluded":"Parallax, the radial-velocity perspective term, aberration and refraction; each is below the accuracy of the catalogued positions themselves. An object with no published proper motion comes back where the catalogue has it rather than at a fabricated zero, and says so with a null pm_ra_mas_yr. A body with no fixed position is not propagated at all — its place comes from an ephemeris, which is what /api/v1/visible answers with."},"slug":"rx-j1131-1231","name":"RX J1131-1231","class":"quasar","category":"black_hole","object_type":"Quasar","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":12709230118.791039,"distance_method":"luminosity distance from a published redshift, flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":172.96474,"dec_deg":-12.53298,"epoch_ra_deg":173.304515,"epoch_dec_deg":-12.681225,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Crater","discovered":"2003","featured":true,"url":"https://spacecatalog.org/object/rx-j1131-1231","radius_km":null,"radius_kind":null,"data_quality":null,"description":"A lensed quasar whose X-ray spectrum gave the first spin measurement for a black hole this far away: it turns at about half the speed of light. Spin is a record of how the hole was fed, so measuring it anywhere but nearby is a statement about the history of the whole population.","properties":{"redshift":0.65427467,"accretion":"quasar"},"designations":[{"catalog":"Common name","designation":"RX J1131-1231"}],"source":{"id":"curated","name":"SpaceCatalog curated data","url":"https://spacecatalog.org/releases","license":"CC-BY-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}